Variable inductance coil



y 31, 1932- (3. F. RUDOLPH ET AL 1,360,722

VARIABLE INDUCTANCE COIL Filed April 15, 1930 2 Sheets-Sheet l 1 z I l A TTORNEY May 31, 1932- c. F. RUDOLPH ET AL 1,850,722

VARIABLE INDUG'IANCE CO IL Filed April 15, 1930 2 Sheets-Sheet 2 awawfomo A TTORNEY Patented May 31, 1932 UNliiiii} STATES PAT'ENT OFFICE CORRIE 'F. RUDOLPH, OF WASHINGTON, DISTRICT OF COLUMBIA, AND CHARLES O. VER- MILLION, OF EAST ORANGE, NEW JERSEY VARIABLE INDUGTANCE COIL Application filed April 15,

Our invention relates broadly to high frequency inductance systems and'more particularly to a construction of high frequency inductance by which accurate amounts of inductance may be effectively connected in the tuning circuit of a transmitter. ()ne of the objects of our invention is to provide a construction of high frequency inductance system whereby accurate amounts of inductance may be effectively included in the tuning circuit of a transmitter.

Another object of'our. invention is to provide a construction of high frequency inductance system wherein a slidably adjustable member may be driven longitudinally of a high frequency inductance coil to selected positions along the coil for cutting in or out of the circuit a selected number of turns of the inductance system. 'Still another object of our invention is to provide'a construction of variable cont-act mechanism for high frequency inductance wherein good electrical contact may be established between an adjustable member and a selected position along the inductance coil for rendering a selected number of turns or parts thereof in the inductance system effective'in a high frequency circuit.

Other and further objects of our invention reside in the construction of a high frequency inductance system as set forth more fully in the specification hereinafter following by reference to the accompanying drawings, in which:

Figure 1 is a cross-sectional view taken through the high frequency inductance system of our invention and showing the adjustable slide movable to selected positions along the high frequency inductance system; Fig. 2 is a lateral crosssectional view through the high frequency inductance system on line 2 2 of Fig. 1; Fig. 3 is a fragmentary crosssectional view through the inductance system looking in the direction of line 33 in Fig. 1; Fig. 4 is a cross-sectional view on line 44 of Fig. 1 through the adjustable slide which is movable longitudinally with respect to the inductance system; Fig. 5 is a fragmentary view illustrating one method of mounting the end of the high frequency 1930. Serial No. 444,506.

inductance with respect to the insulated frame of the inductance system; and Fig. 6 is a detailed fragmentary View illustrating the structure we provide for reducing friction between the movable slide and the longitudinally extending drive system which pro jects through the high frequency inductance.

In high frequency signaling systems it is necessary to accurately adjust the effective inductance which is connected into the high frequency signaling circuit. It is essential to provide means for adjusting the effective inductance in the transmission circuit in order that the effective value of the inductance may be rapidly increased or decreased. It is essential in high frequency signaling systems that losses due to poor conductivity and incomplete contact be reduced to a minimum. lVe have found the structure of our invention highly efficient and successful in its operation. The structure of the inductance system has been highly simplified so that the manufacture and assembly of the inductance system is relatively simple. i v I In referring to the drawings in detail the high frequency inductance coil has the turns thereof designated by reference character 1 constituted by copper ribbon having a high degree of conductivity, the turns of the copper ribbon being supported in slots formed in the inner edges of the longitudinally ex tending insulated strips 2. The strips 2 are secured at their ends to the end of plates 3 and 4 also composed of insulating material. In order to properly mount the longitudinally extending strips 2 between the end plates 3 and l, each plate is provided with radially disposed slots 30 through which bolt members 31 extend, the bolt members passing through flange devices 82 pass through the slots 80 and enter theends of the insulated strips 2, thereby firmly securing the insulated strips in position. e prefer to manufacture the insulated frame of the inductance system from isolantite. Because isolantite which is a synthetic porcelain has such high shrinkage properties, the bearing surfaces of the end plates 8 and d are each provided with offset faces which I have designated at 33, 33a, 3% and 34a, which faces may be ground to secure proper dimensions for the inductance frame. The fact that the longitudinally extending insulated strips are slotted on the inner faces thereof enables the inductance 1 to have its turns spirally or helically wound and positioned between the several longitudinally ere tending strips for the location of the inductance coil in position within the frame of the coil. Passing centrally through the frame we provide a lead screw 5 having threads of the same pitch as the pitch of the turns of the in ductance coil 1. The lead screw 5 has a reduced portion 5a of cylindrical cross-section at the end thereof having a further reduced portion 50 extending therefrom and passing through anaperture 6a in the metallic plate 6. The reduced portion 50 is substantially polygonal in cross section and the aperture 611 in which the extended portion 50 extends correspondingly shaped. A sleeve 5?) fits over the reduced portion 5a of the lead screw 5 and provides a bearing for the rotatable sleeve 14. Fig. 2 illustrates more clearly the manner in which the projection 50 on the lead screw 5 passes through the a erture 6a in the plate 6. The metal'plate 6 serves as an anchor for the end of lead screw 5 which is secured thereto by screw member 35. Inasmuch as the lead screw 5 is permanently anchored by screw member 35 in the end plate 6, movement of the slide 21 along the lead screw 5 is effected by means of the sleeve 14 which er:- tends over the lead screw 5 and readily turns about the end of the lead screw 5 adjacent the plate 6, being maintained in spaced relation with respect thereto by the resilient device 24 having a multiplicity of slotted arms in engagement between the end of sleeve 14 and the plate 6. Rotary movement is imparted to sleeve 14 by means of a rotary shaft 10 which is journaled in end plate 3 of the frame of the inductance system, the inner end of shaft 10 carrying an enlarged portion 13 thereon which is connected by pin 15 with the sleeve 14. The lead screw 5 terminates short of the end of the head .13 on shaft 10 so that while lead screw 5 remains stationary the head 13 of shaft 10 revolves and imparts rotating movement to the sleeve 14. id e provide a bearing plate 11 secured by screw members 36 to the end plate 3, the bearing plate serving as a support for the bushing 12 which accurately aligns the sleeve 14 within the inductance frame. The slide 21 is shiftable with respect to the longitudinal axis of the high frequency inductance by reason of the engagement of screw device 18 with the threads on the lead screw 5. The screw device 18 passes through the slide 21 in a direction normal to the axis of the slide 21 and reduced in cross-section on the end thereof as represented at 19. A pair of independent sleeves which we have designated at 20 and 20a are carried by the reduced end portion of the screw 18. Sleeve 20 serves as a roller bearing for reducing the friction in the movement of the slide with respect to lead screw A slot 17 extends longitudinally of sleeve 14 and serves as a guide for pin 18 which projects therethrough.

In order to prevent lost motion between the slide 21 and the sleeve 14, we provide resilient tubular extensions or contact fingers 22 on slide 21 for establishing better electrical connection between the sleeve 14 and the moving parts, and increasing the accuracy of the mechanical movement of the parts one with respect to another. The slide 21 carries a pivotal member 37 thereon pivoted as shown at 38 in a block 39 which is secured by means of screws 40 to the slide 21. The pivotal member 37 carries brush members 41 and 42 which are secured on opposite sides thereof by screw members 43, which brush members engage opposite sides of the strip like turns 1 of the high frequency inductance. A spring member 44 completes the electrical connection between slide 21 and brushes 41 and 42 so that no losses are expended through the pivotal mounting of the contact member. The spring member 44 serves not only as a circuit conductor but also as a resilient device for mounting the brushes 41 and 42 in a radial position.

Movement is imparted to shaft 10 through a coupling member 45 which may be recessed as indicated at 36 to receive the projecting end of the shaft 10. The shaft 10 is suitably slotted as shown at 47 to receive pin 48 in coupling member 45 enabling the coupling member 45 and shaft 10 to be driven simultaneously. The ends of the inductance are brought out to binding posts 4.9 and 50 on the opposite end plates 3 and 4. By revolving the brushes 41, 42 the effective number of turns of the inductance in the high frequency circuit may be readily selected.

Vi e have described a preferred form of our invention but we desire that it be under stood that modifications may be made and that no limitations upon the invention are intended other than are imposed by the scope of the appended claims.

What we claim as new'and desire to secure by Letters Patent of the United States is as follows:

1. A high frequency inductance systeu'i comprising an insulated frame, an. inductance consisting of a metallic strip spirally wound and disposed. within said insulated frame, a shaft member extending through said inductance, a slide adjustable along said shaft member, a resilient contact device extending in a adial direction from said slide and establishing wiping contact with opposite faces of the turns of the inductance, and means for driving said slide longitudinally with respect to said inductance for varying the position of said resilient contact along the inductance.

2. A high frequency inductance system comprising an insulated frame, a helical strip of conductive material supported within said frame, a stationary screw threaded member ext-ending longitudinally through said inductance, a rotatable sleeve enveloping said shaft, a slider having means extending through said sleeve and engaging said stationary screw threaded member, said slider being controllable by the rotation of said sleeve, an arm extending radially from said slide-and a contact carried by the extremity of said arm, said contact including a pair of resilient jaws embracing opposite faces of the turns of said inductance and adjustable along the turns of the inductance for selecting the effective number of turns therein in accordance with the rotation of said sleeve.

3. A high frequency inductance system comprising an insulatedframe structure, a helical inductance of conductive strip supportedwithin said insulator frame structure, a shaft member extendin centrally through said frame structure, said shaft member having screw threads cut thereon and being fixed in position with respect to one end of said frame structure, a sleeve enclosing said shaft member and having a longitudinally extending slot in one side thereof, means for rotatably driving said sleeve from one end of said frame structure, a slide enveloping said sleeve, a member carried by said slide and projecting through said slot and extending between the'lscrew threads on said shaft whereby said slide may be moved longitudinally along said frame, a radially cxte ding contactor carried by said slide,'e.nd jaws on said contactor engaging opposite faces of the turns of said inductance whereby selected amounts of said inductance may be effectively included in a high frequency circuit.

4. In a high frequency inductance system, an insulated frame structure, a helical. inductance supported by said frame structure, means extending centrally through said frame structure, said means including a fixed screw threaded shaft and a concentrically disposed rotatable sleeve enveloping said shaft, a slide longitudinall movable along said sleeve and having a projecting member extending through a slot in said sleeve and between adjacent screw threads on said shaft, a radially projecting arm pivotally mounted on said slide, brush members carried by said arm for engaging opposite faces of the turns of said inductance, means forimparting rotary movement said sleeve for revolving said slide and driving said slide along said shaft under control of the screw threads which act upon member projecting therebetween.

5. In a high frequency inductance system, an insulated frame structure, a helically wound inductance carried by said frame structure, a member extending centrally through said frame structure, a revolvablc and longitudinally movable slide operated by said member,said slide including an arm pivotally connected therethrough and extending radially therefrom substantially in alignment with the turns of said inductance, brush members carried by opposite sides of said arm and engageable with opposite sides of the turns of inductance and resilient means for maintaining said arm in a position substantially normal to the axis of said slide.

6.. A high frequency inductance system comprising an insulated frame structure, a helically wound inductance having the turns thereof supported within said frame structure with the turns protruding toward the central axis of said frame structure, a member extending centrally through said frame structure, a slide rotatably and longitudinally movable along said member, a pivotally mounted arm connected to said slide, said arm extending radially from said member, resilient means for maintaining said arm in I a plane substantially normal to the axis of said slide, brush members carried by opposite sides of said arm and engaging opposite faces of each turn of said inductance whereby an effective number of turns in said inductance may be selected for inclusion in a high frequency circuit connected with said inductance.

7. In a high frequency inductance system, an insulated frame structure, a screw threaded member centrally mounted from one end of said framestructure, a rotary sleeve en veloping said shaft member and adjustable from the opposite end of said frame structure, a high frequency inductance including a multiplicity of turns of conductive strip located interiorly'of said frame struc ture, a slide carried by said sleeve, said slide having a radially extending arm with brushes thereon adapted to engage opposite faces of each turn of the conductor, and means carried by said slide and projectable between the screw threads of said centrally extending shaft whereby rotary movement imparted to said sleeve and to said slide operates to advance said slide with respect to said sleeve for changing the contacting position between said brushes and the turns of said inductance for controlling the effective number of turns in said inductance system.

8. A high frequency inductance system comprisingan insulated frame structure, a helical inductance having the turns thereof centered within said insulated frame structure, a centrally extending shaft within said frame structure, said shaft comprising a. fixed screw threaded member extending from one end of said frame structure and a rotary sleeve enveloping said fixed screw threaded member and operative from the opposite end of said frame structure, sald sleeve having a longitudinally extending slot formed thereon, a slide movable over said sleeve, a member" carried by'said slide and projecting between the screw threads formed on said fixed screw threaded member, an arm pivotally mounted on said slide and a resilient member connected in one end ofsaid slide and at the other end of said arm for maintaining said arm in a plane substantially normal to the axis of said fixed screw threaded member, brushes carried on opposite sides of said arms and engageable with the opposite faces of each turn of the inductance, and means for imparting rotary movement to said sleeve for shifting said slide to selected positions along said sleeve for varying the effective number of turns in said inductance system.

9. In an inductance system, a helically wound inductance coil, a contactor for varying the effective number of turns in'said inductance coil including aslider movable longitudinally with respect to said helically wound inductance coil, a screw threaded shaft extending axially of said inductance coil, a radially extending arm connected with said slider and projecting to a position adjacent the inside of the turns of said inductance coil, a rotatable sleeve enveloping said shaft, a pin member carried by said slider and projecting through a longitudinal slot in said sleeve, a' roller mountedon said pin member and extending between adjacent threads of said "screw threaded shaft, spring contacts carried on the end of said radially extending arm and establishing wipingconnection with the turns of said inductance and means for imparting rotary motion to said sleeve for moving said pin with respect to said screw threaded shaft for advancing said slider with respect to'said shaft and control ling the effective number of turns in said inductance system.

10. Tn an inductance system, a helically wound inductance coil, a movable contactor for said inductance system comprising a slider adapted to move longitudinally over a central member projecting through an inductance, said slider including a solid portion and a split resilient portion frictionally engageable with said central member. and an arm resiliently connected to the solid portion of said slider and having means thereon for engaging the opposite faces of each turn of the inductance for selecting the effective number of turns of inductance in said inductance system as said slider is shifted in po sition. V

11. A high frequency inductance system comprising an insulated frame structure, a helical inductance centered within said insulated frame structure, a member extending centrally through said helical inductance,

said member including a screw threaded shaft connected to said frame structure at one end and a rotatable sleeve enveloping said screw threaded shaft and rotatable from the opposite end of said frame structure, a slide movable along said sleeve, said slide including a solid portion surrounding said sleeve and a resilient portion frictionally engaging said sleeve, an arm pivotally mounted on said sleeve, brushes carried by said arm and engaging the turns of said inductance, resilient means for maintaining said arm substantially in alignment with the turns of said inductance, and a roller member extending through said sleeve and projecting between the screw threads on said screw threaded shaft whereby rotary movement imparted to said sleeve operates to shift the position of said slide for varying the effective number of turns in said inductance.

12. In a high frequency inductance system, an insulated frame structure, a helical inductance centered within said frame structure, a member extending axially through said inductance, said member including a screw threaded shaft connected to one end of said frame structure and a rotating sleeve embracing said screw threaded shaft and rotatably adjustable from the opposite end of said frame structure, a slide movable along said sleeve, a contacting arm for said inductance carried by said slide, a pin member carried bysaid slide and projecting through a slot in said sleeve, said pin member providing a bearing on a roller transverse to the axis of said slide, said roller providing a rolling friction connection between said slide and said screw threaded shaft for the advancement of said contacting arm along the turns of said inductance for controlling the effective number of turns in said inductance system.

CORRIE F. RUDOLPH. CHARLES O. VERMILLION. 

